Question

In a 100 m race, a runs at 6 km/hr. a gives b a start of 4 m and still beats him by 4 sec. find the speed of b

Answer 1

for person a:

D₁ = distance travelled by person a = 100 m

v₁ = speed of person a = 6 km/hr = 6 (5/18) = 5/3 m/s

time taken by person "a" to complete the race is given as

t₁ = D₁ /v₁ = 100/(5/3) = 60 sec

for person b:

D₂ = distance travelled by person b = 100 - 4 = 96 m

v₂ = speed of person b =

t₂ = time taken by person "b" = 60 + 4 = 64 sec

time taken by person "b" to complete the race is given as

t₂ = D₂ /v₂

64 = 96/v₂

v₂ = 1.5 m/s

v₂ = 1.5 (18/5)

v₂ = 5.4 km/h